Pneumonia is an illness, usually caused by infection, in which the lungs become inflamed and congested, reducing oxygen exchange and leading to cough and breathlessness. It affects individuals of all ages but occurs most frequently in children and the elderly. Among children, pneumonia is the most common cause of death worldwide. Historically, in developed countries, deaths from pneumonia have been reduced by improvements in living conditions, air quality, and nutrition. In the developing world today, many deaths from pneumonia are also preventable by immunization or access to simple, effective treatments. However, as we highlight here, there are critical gaps in our understanding of the epidemiology, etiology, and pathophysiology of pneumonia that, if filled, could accelerate the control of pneumonia and reduce early childhood mortality.
J. Anthony G. Scott, W. Abdullah Brooks, J.S. Malik Peiris, Douglas Holtzman, E. Kim Mulholland
Submitter: Cristiana M. Nascimento-Carvalho | firstname.lastname@example.org
Authors: 2Fernando Ferrero and 3Maria R. A. Cardoso
<sup>1</sup>Federal University of Bahia School of Medicine, Salvador, Brazil. <sup>2</sup>Hospital General de Niños Pedro de Elizalde, Buenos Aires, Argentina. <sup>3</sup>University of São Paulo, Faculty of Public Health, São Paulo, Brazil.
Published July 7, 2008
The comprehensive review by Scott et al. (1), addressing the globally important problem of childhood community-acquired pneumonia (CAP), informed that the impact of antimicrobial resistance on the management of childhood CAP remains unclear. Streptococcus pneumoniae has been recognized as the most common bacterial agent of CAP and the prevalence of disease caused by penicillin resistant S. pneumoniae has increased worldwide (2). Therefore, an urgent issue is whether penicillin is effective to treat pneumococcal pneumonia caused by penicillin resistant strains. In 1995, a South African study showed that the rate of improvement was similar when 78 children with pneumococcal pneumonia caused by either penicillin sensitive S. pneumoniae or intermediate resistant strains were treated with ampicillin or an equivalent β-lactam agent: 93% of children infected with susceptible strains responded and 88% of those infected with intermediate resistant strains responded (OR=1.9; 95%CI: 0.3-15.9) (3). In 1999, a study conducted in Uruguay and Argentina enrolled 75 patients with pneumococcal pneumonia treated with penicillin or ampicillin and there was no significant difference in mortality between the 52 patients infected with penicillin-susceptible S. pneumoniae and the 23 patients infected with highly penicillin-resistant strains (penicillin minimal inhibitory concentration [MIC] ≥2μg/mL) (RR=1; 95%CI: 0.8-1.1)(4). Another study, carried out in Latin America, has been published recently and the authors concluded that high-level S. pneumoniae penicillin resistance was not associated with failure to response to treatment with penicillin among children with pneumococcal pneumonia, meaning that penicillin remains the drug of choice for the treatment of children with severe pneumonia, when administrated at a dose of 200,000 units/kg/day, in areas where highly penicillin-resistant pneumococcal strains are present (MIC<2μg/mL) (5). The study in Latin America was a prospective, multicenter investigation conducted among 236 children and the analysis was adjusted for confounding variables, there was no co-morbidity, and the patients were admitted with disease of the same severity. Therefore, the sample size was appropriate and the results are valid for the general population. In 2008, the U.S. Clinical and Laboratory Standards Institute adopted new penicillin MIC breakpoints for cases of pneumonia (6). The new breakpoints define susceptible strains as responsive to penicillin MIC <2μg/mL, whereas the old breakpoints defined susceptible strains as those with penicillin MIC <0.06μg/mL. The upward shift of the breakpoints was to parallel results in vitro with treatment effectiveness in vivo. So, one must conclude that currently, the evidence points to penicillin as effective for the treatment of pneumococcal pneumonia if the causative pneumococcal strain has a penicillin MIC of <2μg/mL. However, continuous research is necessary to monitor the evolution of pneumococcal MIC and penicillin effectiveness when the penicillin MIC is over 2μg/mL.